Semipermeable membranes may be used for a wide variety of separations involving liquid-liquid separations, liquid-liquid solid separations and gas-gas separations. The membranes which are employed for these purposes usually comprise various organic polymers or mixtures of organic polymers either alone or supported on a porous backing material. For example, semipermeable membranes which are used in desalination processes can comprise cellulose acetate polymers composited on a porous support which acts as a backing for the membrane, thin film composite membranes comprising polymeric compounds such as polyethyleneimine, epiamine, polyethylene, polypropylene films also composited on a porous support such as a polysulfone member, etc. Likewise, gaseous separation membranes may comprise polymeric membranes of cellulose nitrate or cellulose acetate, support membranes having a polymer such as dimethylsilicone, styrene, silicon-carbide copolymers composited thereon, as well as thin film membranes such as polymethylpentene polymers. In addition to these membranes, other permselective membranes such as heteropoly acids may be employed for separating gases such as hydrogen from mixtures of gases in a gaseous stream.
In a majority of cases, the admixture of an organic compound, especially in a polymeric state, with an inorganic compound, results in a phase separation, the two systems being immiscible in nature. However, it has now been discovered that a polymer-blended membrane may be fabricated by admixing a phosphoric acid or sulfuric acid with an organic polymer which is at least compatible with the acid to form a polymer-blended composition of matter, said composition of matter being utilized as one component of a finished membrane which may be used in a gas separation process. The membrane, which is composited on a solid support, possesses unexpected properties which will enable the aforementioned membrane possessing increased strength as well as being highly selective to certain gases to therefore find a use in such separations involving a gas such as hydrogen.